Shot-firing device



Aprll 28, 1925.

J. lB. DE HART SHOT FIRING DEVICE Filed July 50, 1924 /NvENToR JOSEPH BERTRAM DEI/ARK ATTORNEYS Patented Apr. 28, 1925.

UNITED STATES PATNT- rl1 SHOT-HRING DEVICE,

Application led July 30, 1924. erial No. 729,106.

To all whom z't may concern:

Be it known that I, JOSEPH BERTRAM DE HART, a subject of the King of Great Britain, and a resident of the city of Lethbridge, in the Province of Alberta, Canada, have invented certain new and useful llmprovements in Shot-Firing Devices, of which the following is a specification. y My invention relates to improvements in shot tiring devices, the objects of which are to provide means whereby an electrical connection may be safely made to ignition bat-A teries when shot firing in mines and other situations where inflammable gas is likely to be encountered.

The invention consists essentially of a tubular body adapted to be connected to any ignition battery in which the conductor wires from the battery are disposed, and a plug adapted for connection tothe shot i niter, which is provided with termina s which form a contact with the leads within the tubular body, as will be more fully described in the following specification, in which:

Fi 1 is a sectional view of my invention showing the top of the battery to which it is tted.

Fig. 2is a plan view looking down. p

In the drawings like characters of reference indicate corresponding parts in each figure.

The numeral 1 indicates a battery of any suitable type havin binding posts 2 and 3 repectively. 4 is a inged cover to the bat tery to which the tubular body 5 1s attached by a pair of lugs 6. The body 5 is provided with a lower parallel bore 7 and an upper parallel bore 8 which is threaded at its upper end as at 9. In the upper bore 8 an insulating sleeve 10 is itted which is adapted to seat u on an insulating washer 11, and

bearing own upon the sleeve 10 is a screw cap 12 havin a plurality of air vents 13 therein. `Wit in the cap a pair of gauze discs14 are fitted which are spaced apart by a collar 15 and are su ported from the sleeveilO by a further col ar 16. The upper portion of the lower bore 7 is provided with an insulating sleeve 17.

The numeral 18 indicates a contact sleeve which is recessed and threaded as at 19 forw the purpose of holding the inner contact sleeve 20 in position. The numeral 2Q indicates the inner Contact sleeve rovlded with an external flange 21 dispose within the threaded recess 19 ofthe contact sleeve 18 and is insulated therefrom by a pair of lnsulatlng washers 2,2, the sleeve 20 bein held m'position by an externally threaded collar 23.

'lihe numeral 24 indicates a wire from whlch the electrical current is led :from the blnding post 3 of the batte The numeral 25 indicates a wire from w ich the current 1s led from the binding ost 2 of the battery to the inner contact seeve 20, through a screw plug 26 which is screwed into the inner sleeve and is tightenedup against an insulating collar 27. The screw plug 26 is provlded with a central `orifice 28 for the purpose of permitting the'free escape of air or gas from the tubular body 5 as the connector rod 31 is inserted.

The numeral 29 indicates a contact plunger shdably within the inner contact sleeve 20 which is downwardly pressed by a spring 30. The numeral 31 indicates a connector rod which is preferably formed with a tube 32 havlng an external diameter substantially equal to the lower bore 7 ofthe tubular body 5 and which is provided with a plug 33 of non-conducting material reduced at its upper end and provided with: an inward anged collar 34 of a diameter equal to that ofthe recess 35 of the outer-contact sleeve 18 so that as the connector rod and its collar 34 are .pushed upwards into place, the air contained within the lower portion of the body yis forced upwards through the orifice 28 of the screw cap 26.

rlihe numeral36 indicates a cap covering the lower end of the tube 32, having connector plugs 37 and 38 respectively disposed therein, to which wires 39 leading to the firing charge are connected by connector screws 40. A wire is led from the connector plug 38 to the contact collars 34 and a urt er wire is led l from. the plug 39 through the axis of the plug 33 terminatin in a button 41 which forms a contact wit the contact lunger 29.

Having tiius described the several parts of my invention 1 will briefly explain its operation.

When the wires 39 leading from the charge are connected to the connector plugs 37 and 38 it suces to thrust the rod 31 upwards into the tubular body 5 forcing the air upwards to discharge through the gauze dises '14 and the air vents 13, prior to the electric'al contact being made between the contact collar 3ft-and the contact sleeve 18 and between the button 4l and the contact plunger 29.

Should the atmosphere 1n which the device is used be im regnated with combustible `1 gas and a spark e produced at the contact points when the electrical circuit is closed, the flame produced by the igmtlon of the gas will be confinedwithin the `tubular body and the resulting expansion taklng placeupwards through the ganzes 14 which will prevent the passage of the ame, and any llame striking downwards within the conlincd annular space between the rod 31 and the walls of the body 5 will be spent and cooled before reaching the lower extremlty 'of the bore 7.

-What I claim as my invention is:

1. A shot tiring device comprising a tubular member, a pair of contacts mounted 1n the tubular member and insulated therefrom and from each other, a nonconducting contact bearing member carrying contacts adapted to successively engage the contacts of the tubular member as they are thrust one within the other, and shot ring wires connected to the contacts of the contactbearing member.

2. A shot firing device comprising a tubular member, a pair of contacts mounted in the tubular member and insulated therefrom and from each other, a nonconducting contact bearing member carrying contacts adapted to successively engage the contacts of the tubular member as they are thrust one within the other, and shot firing wires connected to the contacts of the contact bearing member, and means for preventing outward dashing as the contacts engage.

3. A shot iring device comprising a tu' bular body having a screened and vented upper chamber and an open ended lower chamber, a pair of electrical contacts carried in the lower chamber and adapted for connection to an ignition battery, a connector rod of substantially similar diameter to the lower chamber adapted for insertion into the lower chamber and having electrical contacts corresponding to those inthe lower chamber, and means for connecting a pair of Shot firing wires to the connector.

4. A shot tiring device comprising a tubui lar body having a screened and vented upper chamber and an open ended lower chamthe lower chamber and adapted for connection'to an ignition battery, a connector rod of substantlally similar diameter to the lower chamber adapted for insertion into the lower chamber and having electrical contacts corresponding to those in the lower chamber, means for connecting a air of shot firing wires to the connector, an means for discharging the air normally residing in the lower chamber through the vented upper chamber as the connector rod is thrust into the tubular body.

5. A shot ring device comprising a tubular body having an open ended lower' chamber, a pair of electrical contacts carried in the lower chamber and adapted for connection to an ignition battery, a connector rod of substantially similar diameter to the lower chamber adapted for insertion into the lower chamber, a pair of electrical contacts corresponding to those in the lower chamber, means for connecting a pair of shot firing wires to the connector contacts, means for forming connection between one contact in the lower chamber and the corresponding contact of the rod when the rod is partially thrust into the tubular body, and for forming a yielding connection between the remaining pair of contacts as the rod is thrust to its ultimate position within the hollow body.

.6. A shot tiring device comprising a tubular body adapted for attachment to an ignition battery, a screened upper chamber and an open ended lower chamber to the-body, insulated contacts adapted for connection ber, a pair of electrical contacts carried in from the battery disposed within the lower JOSEPH BERTRAM DE HART.

Witnesses WM. MACGREGOR,

C. J. DONALDSON. 

